An Apple patent application spotted Thursday by AppleInsider shows a system for detecting unusual motion via a portable gadget’s accelerometer which would sound an alarm, making said device harder to steal without causing unwanted attention. The system is a simple one, without the kind of sophisticated face detection we saw in a previous application, but it could be much more effective for curbing thefts at the moment they occur.

The Apple application describes a system by which an accelerator sensor is triggered by movement which qualifies as a “theft condition,” which would mean not just any motion, but specifically sudden or sudden changes. Obviously the worry is that in using a system like this, just about any action could trigger it – what’s the difference between hastily grabbing your iPhone when you’re late for an appointment, or a thief grabbing it quickly off a college cafeteria table when you’ve got your head turned?

To counter that kind of confusion, Apple describes a system through which a signal filter is a first step to eliminate completely innocuous action, like calmly carrying a device in a pocket, as well as specialized theft detection circuitry tuned to “detect certain acceleration frequency spectra characteristic of theft.” I still can’t help but hear the sound of countless car alarms going off in the street without justifiable cause, but Apple’s system would hopefully be more sophisticated and less subject to false alarms, should it ever make it to market.

Once triggered, the theft detection system would provide users with customizable alarm options, allowing them to select specific audio or visual warnings, a custom message for the display, the volume of audio alerts and more. Users could also tweak sensitivity, if they find they’re triggering it accidentally as described above. Once the alarm is triggered, a timer determines how long someone has to disable it before the phone is locked altogether.

Combined with Apple’s previous patent application for detecting when a device is being used by a party who isn’t the owner, this could make iOS handsets and tablets much less attractive targets to potential thieves, which could help counter the rising theft rates of Apple mobile hardware. Instituting this motion-based system, at least as described in the application, would likely require the addition of specialized hardware controllers, so it probably won’t make it to current devices. But in the future, if Apple feels the need to add more peace of mind to its products, this is one way of doing that.